Rotor equipped aerial device



April 27, 1948. H. F. PITCAIRN ET AL 2,440,292

, "ROTOR EQUIPPED AERIAL DEVICE Filed May 5, 194,4

5 l7 r i Y fl/g F 1 (5.14 H /7 v I M I J IIIVII/ENTOR.

- HAROLD I. PITCAIRN ATTORNEYS A Patented Apr. 27, 1948 UNITED STATES PATENT OFFICE ROTOR EQUIPPED AERIALlDEVICE Harold F. Pitcairn, Bryn Athyn, and PaulH. Stanley, "Huntingdon Valley, Pa., assignors to Autogiro Company :of America, :Philadelphia, Pa.,.a.corporatin of Delaware Application 'Mayfi, 1944, Serial No. 534,246

2 Claims. 1

.Thisinvention'relates to aerial devices-and is especially concerned with an aerial device equipped with abladed rotor constructed to pro 'vide -for retarded descent of the device when released or launched atan elevation, for instance, from a bomber-type airplane.

Although a number of features ofthe invention are'capableof adaptation to a wide variety vof specificuses, thein-vention-is particularly advantageous when adapted to an aerial bomb, es-

'peciallyofthe high explosive type. 'It should 'be'meritioned, however,'that the'device maybe used for-dropping cargo of various types from aircraft, and even for carrying an occupant.

device is afforded. In the event of a device constructed to carry an occupant, the controllable means may be manually'op'erated, and "in the event ofa bomb, or a cargo-carrying device, the controllable means may be actuated by remote control-mechanism, for instance, radiocontrol equipment of known type.

'Still another feature of -the'invention is the provision of stabilizing means-desirably in the form-of a fixed fin located-adjacentthe upper end of the body portion. .Such a fin preferably lies in a substantially vertical plane and is 10- catedtoward one side of thebody portion near its upper end, so that when'launched from an aircraft the stabilizing fin will contribute weathercook stability and act to prevent rotation of the body portion about its own axis.

How the foregoing and other objects and advantages are attained will appear more fully from the following description referring to the accompanying drawing in which-- Figure 1 is a side View of an aerial device constructed according to the present invention, with certain parts of the rotor mounting and rotor control mechanism shown in vertical section; and

Figure 2 is a view at right angles to Figure 1.

Referring first to Figure 1, the body portion proper is indicated in outline at 4. This body for instance, a high explosivebomb. The body portion is preferably cylindrical, having a hollow upper portion -5. This portion serves to mount the rotor and carries the stabilizing fin 6.

The rotormay incorporate any desired numher-of blades, a pair of blades 'l-'l being employed in th'eform illustrated, which -'blades are "provided with fork ends-8 pivotally connected by a common pivot-9 with ahub spindle Iii. The blades also have stops l I adapted to engage the upward extension 40a of the hub and thus restrict upward swingingmovement of the blades aboutthe pivot 9.

-With respect to pivot 9, itis preferable to employ a pivot positioned with its axis oblique-to the longitudinal axes of theblades, the obliquity being such that, when viewed in plan, the pivot axis forms an acute angle with the axis of each blade at the'leading side of the blade axis and the blade pitch-to decrease upon upward swinging of the blades and thereby facilitates initiathe outboard side of the-pivot'axis. This causes tion of rotation.

The hubis journalled by bearing 2 in the inner ring l3 of agi-mbalring assembly. Di ametrically opposite-pivotpins, one of whichappears at [4,

serve to pivotallymount the 1 rings I l3 in another "i'ing lfi which in turn is mounted by trunnions l5 in the supporting-lugs l'l.

The-rotor spindle ii) is adapted to be tilted in all directions bymean's of a controlmember #8 "which is connected with the inner r-ing l3 of the g imbal ring assembly. In the case of a mancarrying device the control It may bemanually operated, and inthe case of a remotely controlled cargo-carrying device or aerial bomb, member it maybe coupled with the servo or other actuatin-g motor device of the remotely controlled mechanism.

When the device is first released or launched the air flow across the blades of the rotor acts to swing them upwardly on the pivot 9 to reportion, in one preferred form comprises a bomb,

duced pitch position. The blade stops H, however, prevent the blades from excessive upward swinging movement and thus ensure that the blades occupy appropriate positions for initiation of rotation under the influence of the air how.

The stops are desirably positioned to remain out of engagement after rotation is established, so as not to interfere with blade movements which accompany adjustments of the rotor control or which result from aerodynamic forces in descent. Moreover; the stops H and the angle of the pivot 9 should be arranged so that the permitted upward swinging movement of the blades ward motion of the airplane at the time of launching. This sets up air flow over the stabilizing fin 6 acting to prevent rotation of the body portion about its vertical axis. Actuation of the rotor control will then enable continuance of the same flight path or any desired change in the direction of drifting, and if the control is actuated to change the direction the stabilizing fin will cause the body portion to turn about its vertical axis through a corresponding angle until the fin is again in a trailing position.

In addition to the foregoing, although various features of the invention are adapted to a driven rotor, preferably the rotor is arranged to provide for aerodynamic or autorotative actuation thereof, under the influence of the relative air flow set up by the descent of the device.

In devices adapted to different purposes the required or desired rate of descent may be different, and this can readily be taken care of by appropriate design of the rotor, especially the blades thereof, for instance, by varying the length of the rotor blades, the pitch setting thereof, etc.

Withrespect to the blade pitch angle to be employed, it may be said that appreciable variation is permissible. An appropriate autorotative setting found suitable for the purpose is about 4 or 5 degrees above the no-lift setting calculated with reference to a plane perpendicular to the axis of rotation, when the blades are perpendicular to the rotational axis.

In an embodiment of the invention taking the form of a remotely controlled explosive bomb adapted to be launched from a bomber-type airplane, it is of advantage that the rotor characteristics and especially the length of the blades be selected so as to retard the rate of descent not appreciably more than that required to secure accuracy in operation of the remote control mechanism, since, in this way, at least some penetrating force will be retained.

With appropriate selection of rotor characteristics, the bombardier or other operator of the remote control mechanism may be provided with suflicient accuracy of control to enable direct 4 striking even of a relatively small specific target.

We claim:

1. A motorless rotary wing device adapted to be dropped from a height with its rotor initially inoperative, said device comprising a relatively light rotor having at least one airfoil rotor blade, a body portion adapted to cooperate with a load so that the combined mass of said body portion and the load is relatively heavy compared with said rotor, and rotor mounting structure comprising a pivot adjacent the blade root securing the blade to the body portion in a manner to provide for blade swinging movement to a high coning position responsive to the downward motion of the device through the air, said structure being arranged to provide for decrease of blade pitch to a negative value when the blade is in said high coning position.

2. A motorless rotary wing device adapted to be dropped from a height with its rotor initially inoperative, said device comprising a relatively light rotor having at least one airfoil rotor blade. a body portion adapted to cooperate with a load so that the combined mass of said body portion and the load is relatively heavy compared with said rotor, and means for initiating rotation of the rotor comprising a pivot securing the blade to the body portion in a manner to provide for blade swinging movement to a high coning position responsive to the downward motion of the device through the air, said pivot having an axis oblique to the longitudinal axis of the blade and providing for decrease of blade pitch to a negative value when the blade is in said high coning position.

HAROLD F. PITCAIRN. PAUL H. STANLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,345,159 Freeman June 29, 1920 1,435,190 Leggelo Nov. 14, 1922 1,537,713 Sperry 1 May 12, 1925 1,799,664 Williams Apr. 7, 1931 1,804,869 Gambarini May 12, 1931 1,811,867 Serragli June 30, 1931 1,964,016 Wiley June 26, 1934 2,044,819 Taylor, June 23, 1936 2,068,616 Wilford Jan. 19, 1937 2,181,477 Chupp Nov. 28, 1939 2,192,492 Bennett Mar. 5, 1940 FOREIGN PATENTS Number Country Date 660,793 Germany June 2, 1938 

